Turkey's Minister of Foreign Affairs Mevlut Cavusoglu denied the accusations during a telephone call to his Mongolian counterpart Tsogtbaatar Damdin, according to the Mongolian Ministry of Foreign Affairs.

But officials were not convinced: "We are an independent nation. Do you think anyone can do abductions in our country?" parliamentarian Baasankhuu Oktaybri wrote on Twitter.

The plane took off at 9:25 pm. Akcay was not on it, a Mongolian transportation official said on Twitter.

Turkey accuses Gulen of ordering the July 2016 failed overthrow of President Recep Tayyip Erdogan. He strongly denies the claims.

Gulen's movement built up significant influence in Turkey and overseas, particularly in Central Asia, Africa and the Balkans, especially via its education network.

Ankara has outlawed the movement as a terror organisation but followers insist they promote peace and moderate Islam.

Turkey has carried out a series of overseas operations against suspected members of the movement in places such as Kosovo, Gabon and more recently Ukraine.

Last week a Turkish blogger accused of links to Gulen was deported from Ukraine as part of an operation by MIT while another individual was detained in Azerbaijan recently and sent back to Turkey.

In Turkey over 77,000 people were arrested over alleged links to the movement during a two-year state of emergency imposed after the coup bid in a crackdown criticised by Ankara's Western allies.